/* 码上 · Mashang — 网页版 HUD（色板与 BRAND_GUIDELINES 一致） */
:root {
  --bg0: #07090F;
  --bg1: #0B0F17;
  --surface: #10161F;
  --surface-hi: #16202E;
  --neonCyan: #00E5FF;
  --neonMagenta: #FF2D78;
  --neonGreen: #00FF9C;
  --neonYellow: #F7FF00;
  --textHi: #F4F8FF;
  --textMid: #B4C4DA;
  --textDim: #93A3B8;
  --line: rgba(143, 163, 191, 0.22);
  --mono: "Cascadia Code", "JetBrains Mono", "Fira Code", Consolas, "Courier New", monospace;
  --sans: "PingFang SC", "HarmonyOS Sans SC", "MiSans", "Microsoft YaHei", "Noto Sans SC", system-ui, sans-serif;
  --nav-h: 62px;
}
html[data-theme="light"] {
  --bg0: #F4F6FA;
  --bg1: #FFFFFF;
  --surface: #FFFFFF;
  --surface-hi: #EDF1F7;
  --textHi: #0B1220;
  --textMid: #33415C;
  --textDim: #5A6B85;
  --line: rgba(11, 18, 32, 0.14);
  --neonCyan: #007A8A;
  --neonMagenta: #C01F5C;
  --neonGreen: #007A4D;
  --neonYellow: #8A6D00;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; min-height: 100%; }
body {
  background:
    radial-gradient(1200px 600px at 80% -10%, rgba(0, 229, 255, 0.08), transparent 60%),
    radial-gradient(900px 500px at -10% 110%, rgba(255, 45, 120, 0.08), transparent 60%),
    var(--bg0);
  color: var(--textHi);
  font-family: var(--sans);
  font-size: 15px;
  line-height: 1.65;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}
:focus-visible { outline: 2px solid var(--neonCyan); outline-offset: 2px; }
.skip {
  position: absolute; left: -9999px; top: 0; z-index: 10000;
  background: var(--neonCyan); color: #04121a; padding: 10px 16px; font-weight: 700;
}
.skip:focus { left: 8px; top: 8px; }
.scanlines {
  pointer-events: none; position: fixed; inset: 0; z-index: 9998; opacity: .28;
  background: repeating-linear-gradient(to bottom, rgba(0,0,0,0) 0 2px, rgba(0,0,0,.16) 3px, rgba(0,0,0,0) 4px);
}

/* ---------- 顶栏 ---------- */
.hud-top {
  display: flex; align-items: center; gap: 16px;
  padding: 10px clamp(14px, 3vw, 26px);
  min-height: var(--nav-h);
  border-bottom: 1px solid var(--line);
  background: color-mix(in srgb, var(--bg1) 88%, transparent);
  position: sticky; top: 0; z-index: 60;
  backdrop-filter: blur(10px);
}
.logo {
  font-weight: 800; letter-spacing: 2px; color: var(--neonCyan);
  text-shadow: 0 0 12px rgba(0, 229, 255, .35); font-size: 19px;
  text-decoration: none; flex: none;
}
.logo .slash { color: var(--neonMagenta); }
.logo-sub { font-size: 12px; color: var(--textDim); letter-spacing: 1px; font-weight: 400; }
.nav { display: flex; gap: 8px; margin-left: auto; flex-wrap: wrap; }
.nav-btn {
  display: inline-flex; align-items: center; justify-content: center;
  min-height: 40px; padding: 6px 15px; border-radius: 4px;
  border: 1px solid var(--line); background: transparent;
  color: var(--textMid); font-family: var(--mono); font-size: 13px;
  text-decoration: none; cursor: pointer; transition: color .15s, border-color .15s, background .15s;
  clip-path: polygon(8px 0, 100% 0, 100% calc(100% - 8px), calc(100% - 8px) 100%, 0 100%, 0 8px);
}
.nav-btn:hover { color: var(--textHi); border-color: var(--neonCyan); }
.nav-btn.active { color: #04121a; background: var(--neonCyan); border-color: var(--neonCyan); font-weight: 700; }
html[data-theme="light"] .nav-btn.active { color: #fff; }
.nav-dl { color: var(--neonGreen); border-color: color-mix(in srgb, var(--neonGreen) 45%, transparent); }
.nav-dl:hover { background: var(--neonGreen); color: #04130b; }
.status { font-size: 12px; color: var(--textDim); display: flex; align-items: center; gap: 7px; white-space: nowrap; }
.dot { width: 9px; height: 9px; border-radius: 50%; display: inline-block; flex: none; }
.dot.off { background: var(--neonMagenta); box-shadow: 0 0 8px var(--neonMagenta); }
.dot.on { background: var(--neonGreen); box-shadow: 0 0 8px var(--neonGreen); }
.nav-toggle, .theme-toggle {
  display: none; width: 40px; height: 40px; align-items: center; justify-content: center;
  background: transparent; border: 1px solid var(--line); border-radius: 4px;
  color: var(--textMid); font-size: 17px; cursor: pointer; flex: none;
}
.theme-toggle { display: inline-flex; margin-left: auto; }
.nav-toggle { display: none; margin-left: auto; }

/* ---------- 布局 ---------- */
.view { max-width: 1060px; margin: 0 auto; padding: 26px clamp(14px, 3vw, 22px) 72px; }
.page-head { margin-bottom: 18px; }
.eyebrow { font-family: var(--mono); font-size: 11px; letter-spacing: 3px; color: var(--neonMagenta); text-transform: uppercase; }
.page-title { font-size: clamp(23px, 4.4vw, 32px); margin: 8px 0 6px; letter-spacing: .5px; }
.page-sub { color: var(--textDim); font-size: 14px; margin: 0; }
.section-title {
  color: var(--neonCyan); font-size: 13px; letter-spacing: 3px;
  margin: 34px 0 12px; font-family: var(--mono); text-transform: uppercase;
}
.dim { color: var(--textDim); font-size: 13px; }
a { color: var(--neonCyan); }

/* ---------- 首页 ---------- */
.home-hero {
  display: grid; grid-template-columns: minmax(0, 1.55fr) minmax(0, .85fr);
  gap: 24px; align-items: center; padding: clamp(18px, 4vw, 34px);
  border: 1px solid var(--line); border-radius: 10px;
  background: linear-gradient(160deg, color-mix(in srgb, var(--surface) 92%, transparent), var(--bg1));
  position: relative; overflow: hidden;
}
.home-hero::before {
  content: ""; position: absolute; left: 0; top: 14px; bottom: 14px; width: 2px;
  background: linear-gradient(var(--neonCyan), var(--neonMagenta));
}
.hero-title { font-size: clamp(26px, 5.6vw, 44px); margin: 10px 0 10px; letter-spacing: 1px; line-height: 1.25; }
.hero-sub { color: var(--textMid); font-size: 14.5px; max-width: 46ch; margin: 0 0 20px; }
.hero-actions { display: flex; gap: 12px; flex-wrap: wrap; }
.btn-primary, .btn-ghost {
  display: inline-flex; align-items: center; justify-content: center;
  min-height: 44px; padding: 10px 22px; border-radius: 5px;
  font-family: var(--mono); font-size: 14px; font-weight: 700; text-decoration: none;
  cursor: pointer; border: 1px solid transparent; transition: transform .12s, box-shadow .15s;
}
.btn-primary { background: var(--neonGreen); color: #04130b; }
.btn-primary:hover { box-shadow: 0 0 22px color-mix(in srgb, var(--neonGreen) 55%, transparent); transform: translateY(-1px); }
.btn-primary.small { min-height: 38px; padding: 7px 16px; font-size: 13px; }
.btn-ghost { background: transparent; color: var(--neonCyan); border-color: color-mix(in srgb, var(--neonCyan) 45%, transparent); }
.btn-ghost:hover { background: color-mix(in srgb, var(--neonCyan) 12%, transparent); }
.hero-ring {
  justify-self: center; width: 150px; height: 150px; border-radius: 50%;
  border: 2px solid color-mix(in srgb, var(--neonCyan) 55%, transparent);
  display: flex; flex-direction: column; align-items: center; justify-content: center;
  text-align: center; gap: 2px;
  box-shadow: inset 0 0 26px rgba(0, 229, 255, .1);
}
.ring-value { font-family: var(--mono); font-size: 28px; font-weight: 800; color: var(--neonCyan); }
.ring-label { font-size: 11px; color: var(--textDim); letter-spacing: 2px; }
.ring-rank { font-size: 11px; color: var(--neonYellow); margin-top: 4px; }

.stat-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(150px, 1fr)); gap: 12px; margin-top: 16px; }
.stat-card {
  border: 1px solid var(--line); border-radius: 8px; padding: 14px 16px; background: var(--bg1);
  border-left: 2px solid var(--line);
}
.stat-card.cyan { border-left-color: var(--neonCyan); }
.stat-card.green { border-left-color: var(--neonGreen); }
.stat-card.mag { border-left-color: var(--neonMagenta); }
.stat-card.yel { border-left-color: var(--neonYellow); }
.stat-value { font-family: var(--mono); font-size: 20px; font-weight: 800; }
.stat-label { font-size: 12px; color: var(--textDim); letter-spacing: 1px; }
.stat-sub { font-size: 11px; color: var(--textDim); margin-top: 2px; }

.focus-card {
  border: 1px solid color-mix(in srgb, var(--neonMagenta) 35%, transparent);
  border-radius: 8px; padding: 20px 22px; background: var(--bg1);
  display: flex; flex-direction: column; gap: 6px; align-items: flex-start;
}
.focus-kicker { font-family: var(--mono); font-size: 10.5px; letter-spacing: 3px; color: var(--neonYellow); }
.focus-title { font-size: 21px; font-weight: 800; }
.focus-sub { color: var(--textDim); font-size: 13.5px; margin-bottom: 10px; }

.feature-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 12px; }
.feature-card { border: 1px solid var(--line); border-radius: 8px; padding: 16px; background: var(--bg1); border-top: 2px solid var(--line); }
.feature-card.cyan { border-top-color: var(--neonCyan); }
.feature-card.green { border-top-color: var(--neonGreen); }
.feature-card.mag { border-top-color: var(--neonMagenta); }
.feature-card.yel { border-top-color: var(--neonYellow); }
.feature-title { font-weight: 800; margin-bottom: 6px; font-size: 15px; }
.feature-desc { color: var(--textDim); font-size: 13px; }

/* ---------- 课程列表 ---------- */
.chip-row { display: flex; gap: 8px; flex-wrap: wrap; margin: 16px 0 6px; }
.chip {
  font-family: var(--mono); font-size: 12.5px; padding: 7px 14px; min-height: 36px;
  border: 1px solid var(--line); border-radius: 4px; background: transparent;
  color: var(--textMid); cursor: pointer;
}
.chip:hover { border-color: var(--neonCyan); color: var(--textHi); }
.chip.on { background: var(--neonCyan); border-color: var(--neonCyan); color: #04121a; font-weight: 700; }
html[data-theme="light"] .chip.on { color: #fff; }
.chapter-title {
  font-size: 15px; color: var(--neonMagenta); letter-spacing: 1px;
  margin: 26px 0 8px; padding-bottom: 6px; border-bottom: 1px dashed var(--line);
}
.lesson-list { display: flex; flex-direction: column; gap: 8px; }
.lesson-row {
  display: flex; align-items: center; gap: 14px; padding: 13px 16px;
  border: 1px solid var(--line); border-radius: 7px; background: var(--bg1);
  text-decoration: none; color: inherit; transition: border-color .15s, transform .15s;
  min-height: 62px;
}
.lesson-row:hover { border-color: var(--neonCyan); transform: translateX(2px); }
.lesson-row.done { border-color: color-mix(in srgb, var(--neonGreen) 40%, transparent); }
.lesson-row.locked { opacity: .62; }
.lesson-num {
  font-family: var(--mono); font-size: 15px; font-weight: 700; color: var(--neonCyan);
  width: 42px; text-align: center; padding: 6px 0; border-radius: 4px;
  background: color-mix(in srgb, var(--neonCyan) 10%, transparent); flex: none;
}
.lesson-main { flex: 1; min-width: 0; }
.lesson-title { font-weight: 700; font-size: 15.5px; }
.lesson-sub { color: var(--textDim); font-size: 12.5px; margin-top: 2px; }
.lesson-side { display: flex; align-items: center; gap: 12px; flex: none; }
.lesson-xp { font-family: var(--mono); font-size: 12px; color: var(--neonYellow); }
.lesson-icon { font-size: 14px; color: var(--neonCyan); }
.lesson-row.done .lesson-icon { color: var(--neonGreen); }
.lesson-row.locked .lesson-icon { color: var(--textDim); }

/* ---------- 课程详情 ---------- */
.back-btn {
  display: inline-flex; align-items: center; min-height: 40px; padding: 6px 14px; margin-bottom: 16px;
  border: 1px solid color-mix(in srgb, var(--neonCyan) 40%, transparent); border-radius: 4px;
  color: var(--neonCyan); font-family: var(--mono); font-size: 13px; text-decoration: none;
}
.back-btn:hover { background: color-mix(in srgb, var(--neonCyan) 12%, transparent); }
.lesson-head { border-bottom: 1px dashed var(--line); padding-bottom: 14px; margin-bottom: 8px; }
.lesson-head h1 { font-size: clamp(21px, 4vw, 28px); margin: 6px 0 4px; }
.lesson-head .sub { color: var(--neonMagenta); font-size: 13.5px; }
.lesson-body { max-width: 76ch; }
.lesson-foot { display: flex; gap: 12px; justify-content: space-between; flex-wrap: wrap; margin-top: 34px; }

/* 块 */
.blk-heading { color: var(--neonCyan); font-size: 18px; font-weight: 800; margin: 26px 0 8px; }
.blk-text { color: var(--textMid); margin: 8px 0; }
.blk-tip { color: var(--neonGreen); border-left: 3px solid var(--neonGreen); padding: 8px 14px; background: color-mix(in srgb, var(--neonGreen) 7%, transparent); margin: 12px 0; }
.blk-warn { color: var(--neonYellow); border-left: 3px solid var(--neonYellow); padding: 8px 14px; background: color-mix(in srgb, var(--neonYellow) 7%, transparent); margin: 12px 0; }
.blk-task { color: var(--textHi); border: 1px solid color-mix(in srgb, var(--neonMagenta) 40%, transparent); padding: 10px 14px; background: color-mix(in srgb, var(--neonMagenta) 7%, transparent); margin: 12px 0; }
.blk-task::before { content: "▍任务 "; color: var(--neonMagenta); font-weight: 700; }
.blk-steps { color: var(--textMid); margin: 8px 0; padding-left: 22px; }
.blk-steps li { margin: 6px 0; }
pre.diagram, pre.term {
  background: color-mix(in srgb, var(--bg0) 70%, #000);
  border: 1px solid color-mix(in srgb, var(--neonCyan) 25%, transparent);
  color: var(--neonGreen); padding: 12px 14px; overflow-x: auto;
  font-family: var(--mono); font-size: 13px; border-radius: 4px; white-space: pre;
}
html[data-theme="light"] pre.diagram, html[data-theme="light"] pre.term { background: #F7FAFF; color: #04654A; }
pre.term.preview { border-color: color-mix(in srgb, var(--neonGreen) 30%, transparent); }
.table-wrap { overflow-x: auto; margin: 12px 0; }
table.neon { width: 100%; border-collapse: collapse; font-size: 14px; min-width: 420px; }
table.neon th { background: color-mix(in srgb, var(--neonCyan) 12%, transparent); color: var(--neonCyan); text-align: left; padding: 8px 10px; border: 1px solid var(--line); }
table.neon td { padding: 8px 10px; border: 1px solid var(--line); color: var(--textMid); }

/* 卡片 / 代码 */
.card {
  background: var(--surface); border: 1px solid color-mix(in srgb, var(--neonCyan) 22%, transparent);
  border-radius: 6px; padding: 18px 20px; margin: 14px 0; position: relative;
}
.card::before {
  content: ""; position: absolute; left: 0; top: 12px; bottom: 12px; width: 2px;
  background: linear-gradient(var(--neonCyan), var(--neonMagenta)); opacity: .65;
}
.code-card { background: var(--bg1); border: 1px solid color-mix(in srgb, var(--neonCyan) 28%, transparent); border-radius: 5px; margin: 12px 0; overflow: hidden; }
.code-area {
  display: block; width: 100%; min-height: 76px; background: transparent; color: var(--textHi);
  border: none; outline: none; padding: 12px 14px; font-family: var(--mono); font-size: 14px;
  resize: vertical; line-height: 1.6; tab-size: 4;
}
.code-bar { display: flex; gap: 10px; align-items: center; padding: 8px 12px; border-top: 1px solid var(--line); background: color-mix(in srgb, var(--neonCyan) 5%, transparent); flex-wrap: wrap; }
.btn-run {
  min-height: 40px; background: var(--neonCyan); color: #04121a; border: none; padding: 7px 18px;
  cursor: pointer; font-family: var(--mono); font-weight: 700; font-size: 13px; border-radius: 4px;
}
.btn-run:hover { box-shadow: 0 0 14px color-mix(in srgb, var(--neonCyan) 55%, transparent); }
.btn-run:disabled { opacity: .55; cursor: progress; }
.btn-ghost { min-height: 40px; background: transparent; color: var(--textMid); border: 1px solid var(--line); padding: 7px 14px; cursor: pointer; font-family: var(--mono); font-size: 12.5px; border-radius: 4px; }
.btn-ghost:hover { color: var(--textHi); border-color: var(--neonCyan); }
.run-tag { font-size: 12px; color: var(--textDim); }
.live-region { position: absolute; width: 1px; height: 1px; overflow: hidden; clip: rect(0 0 0 0); white-space: nowrap; }

.out { margin-top: 10px; }
.term-out {
  background: color-mix(in srgb, var(--bg0) 65%, #000);
  border: 1px solid color-mix(in srgb, var(--neonGreen) 28%, transparent);
  color: var(--neonGreen); padding: 10px 12px; font-size: 13px; white-space: pre-wrap;
  border-radius: 4px; min-height: 20px; font-family: var(--mono); overflow-wrap: anywhere;
}
html[data-theme="light"] .term-out { background: #F7FAFF; color: #04654A; }
.term-out.err { color: var(--neonMagenta); border-color: color-mix(in srgb, var(--neonMagenta) 42%, transparent); }
.term-out.empty::before { content: "（无输出）"; color: var(--textDim); }
.snap { margin-top: 10px; }
.snap-title { color: var(--neonYellow); font-size: 12px; letter-spacing: 1px; margin-bottom: 6px; font-family: var(--mono); }
.snap-grid { display: flex; flex-wrap: wrap; gap: 8px; }
.chip .cname, .snap .cname { color: var(--neonYellow); }
.snap .chip { background: color-mix(in srgb, var(--neonYellow) 7%, transparent); border: 1px solid color-mix(in srgb, var(--neonYellow) 30%, transparent); padding: 4px 10px; font-size: 12px; border-radius: 3px; font-family: var(--mono); }
.snap .ctype { color: var(--neonMagenta); }
.snap .cval { color: var(--textHi); }

.verdict { margin-top: 10px; padding: 10px 14px; border-radius: 4px; font-weight: 700; font-size: 14px; }
.verdict.pass { background: color-mix(in srgb, var(--neonGreen) 12%, transparent); color: var(--neonGreen); border: 1px solid var(--neonGreen); }
.verdict.fail { background: color-mix(in srgb, var(--neonMagenta) 12%, transparent); color: var(--neonMagenta); border: 1px solid var(--neonMagenta); }

.quiz-q { color: var(--textHi); font-weight: 700; margin: 8px 0; }
.quiz-opts { display: flex; flex-direction: column; gap: 8px; }
.quiz-opt {
  display: block; width: 100%; text-align: left; padding: 10px 14px; min-height: 42px;
  border: 1px solid var(--line); background: transparent; border-radius: 4px;
  color: var(--textMid); font-family: var(--sans); font-size: 14px; cursor: pointer;
}
.quiz-opt:hover { border-color: var(--neonCyan); }
.quiz-opt.correct { border-color: var(--neonGreen); color: var(--neonGreen); background: color-mix(in srgb, var(--neonGreen) 9%, transparent); }
.quiz-opt.wrong { border-color: var(--neonMagenta); color: var(--neonMagenta); background: color-mix(in srgb, var(--neonMagenta) 9%, transparent); }
.quiz-explain { color: var(--textDim); font-size: 13px; margin-top: 10px; }

.order-list { list-style: none; padding: 0; margin: 8px 0; }
.order-item { display: flex; align-items: center; gap: 10px; background: var(--bg1); border: 1px solid var(--line); padding: 9px 12px; margin: 6px 0; color: var(--neonCyan); font-size: 13px; border-radius: 4px; }
.order-item .idx { color: var(--neonYellow); font-weight: 700; font-family: var(--mono); }
.order-item .oline { flex: 1; min-width: 0; overflow-wrap: anywhere; font-family: var(--mono); }
.order-item button { background: transparent; border: 1px solid var(--line); color: var(--textMid); cursor: pointer; padding: 3px 10px; font-family: var(--mono); min-height: 30px; }

.fill-row { display: flex; gap: 10px; flex-wrap: wrap; margin: 10px 0; }
.fill-input {
  flex: 1; min-width: 180px; min-height: 42px; background: var(--bg1); border: 1px solid var(--line);
  color: var(--textHi); padding: 8px 12px; font-family: var(--mono); font-size: 14px; border-radius: 4px;
}
.fill-input.ok { border-color: var(--neonGreen); }
.fill-input.bad { border-color: var(--neonMagenta); }
.fill-code { margin-bottom: 4px; }

/* ---------- 终端 ---------- */
.repl-term {
  background: color-mix(in srgb, var(--bg0) 68%, #000); border: 1px solid color-mix(in srgb, var(--neonGreen) 30%, transparent);
  min-height: 300px; max-height: 56vh; overflow-y: auto; padding: 12px 14px;
  font-size: 13.5px; white-space: pre-wrap; color: var(--neonGreen); border-radius: 5px;
  font-family: var(--mono); overflow-wrap: anywhere;
}
html[data-theme="light"] .repl-term { background: #F7FAFF; color: #04654A; }
.repl-line-in { color: var(--neonCyan); }
.repl-input-row { display: flex; gap: 8px; margin-top: 10px; align-items: flex-start; }
.repl-input-row .prompt { color: var(--neonGreen); font-weight: 700; padding-top: 10px; font-family: var(--mono); }
.repl-input {
  flex: 1; min-height: 44px; background: var(--bg1); border: 1px solid color-mix(in srgb, var(--neonCyan) 30%, transparent);
  color: var(--textHi); padding: 10px 12px; font-family: var(--mono); font-size: 14px; border-radius: 4px;
  resize: vertical; line-height: 1.6;
}

/* ---------- 角斗场 ---------- */
.arena-list { display: grid; grid-template-columns: repeat(auto-fill, minmax(280px, 1fr)); gap: 14px; }
.arena-card {
  display: block; background: var(--surface); border: 1px solid color-mix(in srgb, var(--neonMagenta) 30%, transparent);
  padding: 16px; border-radius: 6px; color: inherit; text-decoration: none; transition: border-color .15s, transform .15s;
}
.arena-card:hover { border-color: var(--neonMagenta); transform: translateY(-2px); }
.arena-card.done { border-color: color-mix(in srgb, var(--neonGreen) 45%, transparent); }
.arena-card .at { color: var(--textHi); font-size: 16.5px; font-weight: 800; }
.arena-card .ad { color: var(--neonMagenta); font-size: 12px; margin-top: 2px; }
.arena-card .ab { color: var(--textDim); font-size: 13px; margin-top: 8px; }
.arena-card.app-only { border-color: var(--line); opacity: .8; }
.arena-card.app-only:hover { transform: none; }
.arena-card .badge { display: inline-block; margin-left: 8px; padding: 1px 8px; font-size: 11px; font-weight: 700; color: var(--neonYellow); border: 1px solid color-mix(in srgb, var(--neonYellow) 45%, transparent); vertical-align: middle; border-radius: 3px; }
.brief { color: var(--textMid); border-left: 3px solid var(--neonCyan); padding: 9px 14px; margin: 12px 0; background: color-mix(in srgb, var(--neonCyan) 6%, transparent); font-size: 14px; }
.hint { color: var(--neonYellow); font-size: 13px; margin-top: 8px; }

/* ---------- 启动遮罩 ---------- */
.boot { position: fixed; inset: 0; background: var(--bg0); display: flex; align-items: center; justify-content: center; z-index: 500; padding: 20px; overflow: auto; }
.boot.hidden { display: none; }
.boot-box { text-align: center; max-width: 100%; }
.boot-art { color: var(--neonCyan); text-shadow: 0 0 16px rgba(0, 229, 255, .45); font-size: clamp(4px, 1.35vw, 11px); line-height: 1.2; overflow: hidden; margin: 0 0 18px; }
.boot-line { color: var(--neonGreen); font-size: 14px; min-height: 20px; line-height: 1.9; font-family: var(--mono); overflow-wrap: anywhere; }
.boot-actions { display: flex; gap: 10px; justify-content: center; margin-top: 18px; flex-wrap: wrap; }
.boot-actions[hidden] { display: none; }

/* ---------- 页脚 ---------- */
.foot { border-top: 1px solid var(--line); padding: 26px clamp(14px, 3vw, 22px) 40px; max-width: 1060px; margin: 0 auto; }
.foot-row { display: flex; gap: 8px 16px; flex-wrap: wrap; align-items: center; font-family: var(--mono); font-size: 12.5px; color: var(--textDim); }
.foot-row a { color: var(--textMid); text-decoration: none; }
.foot-row a:hover { color: var(--neonCyan); }
.foot-row .sep { color: var(--neonMagenta); }
.link-btn { background: none; border: none; color: var(--textMid); font-family: var(--mono); font-size: 12.5px; cursor: pointer; padding: 0; text-decoration: underline; }
.link-btn:hover { color: var(--neonMagenta); }
.fine { color: var(--textDim); font-size: 12px; margin-top: 12px; line-height: 1.8; }

/* ---------- 提示条 ---------- */
.toast {
  position: fixed; left: 50%; bottom: 26px; transform: translate(-50%, 20px); z-index: 900;
  background: var(--surface-hi); border: 1px solid var(--neonCyan); color: var(--textHi);
  padding: 11px 20px; border-radius: 6px; font-size: 13.5px; opacity: 0;
  transition: opacity .25s, transform .25s; box-shadow: 0 10px 34px rgba(0, 0, 0, .45);
  max-width: calc(100vw - 40px); text-align: center;
}
.toast.show { opacity: 1; transform: translate(-50%, 0); }

/* ---------- 响应式 ---------- */
@media (max-width: 900px) {
  .home-hero { grid-template-columns: minmax(0, 1fr); }
  .hero-ring { width: 122px; height: 122px; }
}
@media (max-width: 760px) {
  .hud-top { flex-wrap: wrap; gap: 10px; padding: 10px 14px; }
  .logo { font-size: 17px; }
  .logo-sub { display: none; }
  .theme-toggle { display: inline-flex; }
  .nav-toggle { display: inline-flex; }
  .nav {
    display: none; width: 100%; margin-left: 0; flex-direction: column; gap: 6px;
    padding-top: 6px; border-top: 1px solid var(--line);
  }
  .nav.open { display: flex; }
  .nav-btn { width: 100%; justify-content: flex-start; padding: 10px 14px; }
  .status { order: 3; font-size: 11px; }
  .view { padding-top: 18px; }
  .lesson-row { padding: 11px 12px; gap: 10px; }
  .lesson-num { width: 36px; font-size: 13.5px; }
  .lesson-title { font-size: 14.5px; }
  .lesson-sub { font-size: 12px; }
  .lesson-xp { display: none; }
  .card, .focus-card { padding: 15px 16px; }
  .foot { padding-bottom: 30px; }
}
@media (prefers-reduced-motion: reduce) {
  * { animation: none !important; transition: none !important; scroll-behavior: auto !important; }
}

/* ---------- 多语言对照块 ---------- */
.blk-compare { margin: 18px 0; display: flex; flex-direction: column; gap: 12px; }
.cmp-col { border: 1px solid var(--line2); border-radius: 10px; padding: 10px; background: var(--card); }
.cmp-head { display: flex; align-items: center; gap: 8px; margin-bottom: 8px; flex-wrap: wrap; }
.cmp-lang {
  font-family: var(--mono); font-size: 11px; font-weight: 700; letter-spacing: .06em;
  text-transform: uppercase; color: var(--magenta, #FF2D78);
  background: rgba(255, 45, 120, .12); border-radius: 4px; padding: 2px 8px;
}
.cmp-note { font-size: 12px; color: var(--dim); }

/* ---------- 过程可视化块 ---------- */
.blk-viz { margin: 18px 0; border: 1px solid var(--line2); border-radius: 10px; padding: 12px; background: var(--card); }
.viz-stage { margin: 10px 0; display: flex; flex-direction: column; gap: 6px; }
.viz-label { font-size: 13px; color: var(--text, #E6F6FF); margin-bottom: 4px; }
.viz-row {
  display: flex; justify-content: space-between; align-items: center;
  padding: 6px 10px; border-radius: 6px; font-family: var(--mono); font-size: 13px;
}
.viz-row.changed { background: rgba(247, 255, 0, .12); color: var(--yellow, #F7FF00); }
.viz-name { color: var(--dim); }
.viz-val { font-weight: 700; }

/* 非 Python 语言的只读代码卡：与可运行卡区分开 */
.code-card .run-tag { font-size: 11px; color: var(--dim); }